In April 2006 old friends of mine, David Frank, the chief executive of Zodiak Media Group, and his wife, Isabelle, rang to say they had seen an advertisement for a house in Majorca and had put in an offer, sight unseen.

In fact, David had never been to Majorca. But the house, built directly into a limestone hillside, with caves as rooms, and further caves and disused rock mines in the grounds, had fired their imagination, and when they did finally visit just before signing contracts, they found it to be as quirkily seductive in reality. Would I like to make the garden, they asked.

Since I had never designed a whole garden for anyone else before, and never so much as wielded a trowel in the Mediterranean, this invitation was rather reckless. But over the years I had had many chats with Isabelle about her various London gardens, she and David had been to my garden in north Wales, and they knew I had seen a lot of gardens in Spain, France and Italy. 'We want you to bring your own vision to our Majorca garden,’ David said. That was my only brief.

I remember taking in the landscape for the first time as we drove from Palma airport to the south-east corner of the island. Sun on the far-off mountains, scruffy little towns with handsome churches, horses grazing in fields of white and yellow marguerites, wild gladioli on the verges.

The Franks’ house was 50 yards above the plain, overhung by bald and fissured rock outcrops, and flanked by extensive runs of limestone pavement, oak and pine trees, among which we found bee orchids and heard the cuckoo-like calls of hoopoes. Below the house was a wilderness acre of wild olives and dark lentiscus bushes, punctuated by stands of opuntia cactus and purple muscari. The only gardened section was the largest of several courtyard areas by the house, with its pomegranate tree, casual beds of roses, oleander, banana and bird of paradise flower, and tangles of bougainvillea, grapevine and morning glory on the walls.

Renovation of the house, which was to be a holiday home for the Franks and their three children, was the priority, so the garden could be, as garden-making ought to be, a slow-fuse project. Indeed, we all saw so little need for rush that we are still working on it five years later, enjoying the gentle process of rumination behind each part of the design and planting.

Nevertheless, that first day we began to clear the mountainous heap of woody debris that we had inherited in the middle of another of the courtyards, and as we did so an extraordinary vision revealed itself. Over the wall, several miles distant, loomed the silhouette of what looked like a castle out of The Lord of the Rings, perched on its own jagged, 500-yard-high hill. It turned out to be the monastery of Sant Salvador. That evening we drove up to it, the road snaking through pine woods and an understorey of cistus bushes and pampas-like ampelodesmos grass.

At the monastery entrance was a well with a brass cup offering a cool drink: 'This water is potable. Do not soil it,’ someone had carefully composed and fired in ceramic tiles without checking the English translation. Sadly, there was no monastery garden from which to take inspiration, but the church was filled with images of the Virgin Mary clutching her white lily, Lilium candidum. So for the design of our own courtyard, I thought we should not only draw in the monastery view, reflecting it in a traditional quartered pattern of beds, edged in low hedging and simply planted with herbs and vegetables, but also make sure we included the Madonna lily.

To help me get to grips with the practicalities of gardening in the Mediterranean, I was keen to meet some local gardeners. Having no Spanish, communication with the neighbours was proving frustrating, but through the internet I tracked down the Majorca branch of the Mediterranean Garden Society, who turned out to be mostly English-speaking expats of assorted nationalities and, as one would expect of gardeners, extremely welcoming. Inviting me to see her garden in the mountains, one of them told me not to be put off by the distance from her gate to her house; it was over four miles. When I got there she had prepared a three-course meal, and invited 30 other guests.

Clearly, however, there was much I had to discover for myself on site, especially since I wanted to indulge in the widest possible spectrum of plants that I had never had the chance to grow before – plants either too tender for Britain or that wanted conditions diametrically opposed to the damp, shady, acidic ones presented by my own Welsh garden. But the two colleagues I invited to work on the garden with me, and to take turns joining me on my bi-monthly visits, have brought to the project considerable hands-on expertise in warm-climate gardening – Stuart Barfoot is the curator of Torrecchia, a leading Italian garden, and James Aldridge, who was assistant head gardener at Highgrove, spends part of the year in South Africa (both also have their own design practices).

But we have all been ambushed by the extreme alkalinity of the soil (pH 8.4), and by the intensity of the summers, which cause native cistus and euphorbia to shrivel and even Majorca’s famous almond trees to drop their leaves just as the main August wave of tourists hits the island. A sere landscape, rasping with cicadas, has its own charm, but around the house and pool you do want summer greenery and colour, and that means a different cast of plants, and water. We have been working on capturing every possible drop of the 20 inches of annual rainfall, and this year will see the completion of our 100-yard-long stone rill, which will wind its way through the olive wilderness, carrying rain from the house’s gutters to a large water tank in the field for recycling in summer.

Gradually, over the past five years, the garden has taken on a series of 10 different planting zones, unified by the rock, walls and wild olives, with David, Isabelle, Stuart, James and our groundsman, Heiko Pagel, all having lively input into the design and their own areas of influence (David is our highways and byways department).

After the Monastery Garden, we embarked on the Mine Garden, a sunken courtyard with a 10-yard drop into a mineshaft and a network of small subterranean limestone quarries. During my first August here, I realised how desperately the eye wants respite from the sun, its glare exacerbated by all our white stone. So I conceived this area as one of cool, green shade.

I thought it would be fun to have water dripping over the mineshaft’s rock overhang, and to enter the mine by stepping stones across a deep, black pool. I also wanted to make allusion to the ancient history of our site, whose caves would almost certainly have been inhabited by Neolithic settlers and the land by their successors of the second millennium BC, who built strange conical megaliths called talayots on the island, possibly as lookout towers. We planted it with groups of primeval cycads, nephrolepis ferns, native fan palms and giant papyrus, found some wicker seats of talayotic shape, and added some reptiles to our pool in the form of four turtles – which, having munched through some expensive lotus plants, are not presently in my good books.

The rock being close to the surface in other parts of the garden, we recycled many of the crumbling drystone walls to create raised planting beds, which we filled with a fertile soil mix and keep moist with drip hose. I did not anticipate that we were creating ideal bed and breakfast facilities for vine weevils, whose grubs seemed to materialise out of nowhere in vast numbers. Although we pledged to run the garden organically, on this occasion I could see no alternative but to do a one-off chemical assault.

Many of these beds, especially near the house, have been planted to be colourful and jungly like a Rousseau painting, so we have been lavish with cannas, shield-leafed colocasias, cane begonias, scented ginger lilies, crinums and jasmines including the splendidly named 'Grand Duke of Tuscany’ – many sourced from our favourite nurseryman on the island, Helmut Michi, a German who in a previous life was a bird-trapper for zoos and, in one of those peculiar connections, turned out to have supplied the African shoebills that I looked after during my 1976 holiday job in Frankfurt Zoo.

Courtyard fountains having been integral to Spanish gardens since the occupying Arabs introduced them in medieval times, we got our architect-builder, José Monserrat, and his craftsmen to build some in traditional design to marry with the house – which is thought to date from the 15th century – and to bring the refreshing sight and sound of water in the hot summer months.

But beyond the old courtyards, there was the opportunity to create a more contemporary look to accompany a new swimming-pool, barbecue and bar. We (David, Isabelle and the team) were all itching to have a go at a cactus garden. In spite of the winter wet and temperatures hovering just above freezing, cacti thrive in Majorca, and there is a large commercial nursery growing them right on our doorstep. Being heavy and vicious, the plants arrived on site enveloped in bubblewrap and had to be manhandled into position by three burly nursery workers. I was amazed to see they had virtually no roots, and we were instructed not to water them for at least a month to prevent them rotting. Unveiled in their architectural splendour, this was instant gardening par excellence.

Much of the 10-acre site, including all of the escarpment and most of the wilderness, we are leaving entirely to nature and its limestone flora. An isolated pocket of wild, rocky ground, however, had been worked on previously and abandoned as scrub, and here I have been experimenting at developing a sort of etherealised version of the island’s maquis. The aim is to produce a rhythmic series of seasonal highlights without soil improvement and with minimal watering, but it is still very much a work in progress. Most successful so far have been the aloes, which produce their orange torches from autumn onwards, and the Mexican salvias, almost every species of which seems to love it here – some, such as blackcurrant S discolor and red S confertiflora, flowering non-stop all year.

Over the past couple of years, we have also been trying our hand at annual meadows – with no watering. In one area we are autumn-sowing a kaleidoscopic mix of our own devising, and in another a calmer sweep of white corn camomile splashed with blue cornflower. This we now plan to interplant with an assortment of spring bulbs we have been testing, including scented cream Gladiolus tristis and wild white freesia.

If I had to choose, I am not sure I would opt for gardening in the Mediterranean over gardening at home, for in spite of our occasional hard winters we can grow a far wider range of plants, and with more ease. But it is wonderful to have sunshine and blue sky as the norm, and to be gardening in the company of praying mantis and swallowtail butterflies. Making this garden continues to be the greatest of adventures.